Radio-telephone cradle connector

ABSTRACT

A cradle connector for a radio-telephone base station has a plurality of terminals mounted in insulative housings the terminal interconnected by a shorting bar inmoulded to the housing. The terminals have spring section and contacts that are depressible against action of the spring to allow relatively large tolerances in the positioning of the telephone with respect to the base station. The contacts have extensions that abut against the shorting bar when the connector is disconnected, whereby one of the terminals is connected to ground so that electrostatic discharges do not damage the base station circuitry. Certain extensions can be removed for some of the terminals if such terminals should not be grounded (e.g. power terminals). The shorting bar could be made of wire that interconnects a plurality of housings during manufacturing and handling for reducing the cost thereof. The cradle connector is thus compact, cost-effective and protected against electrostatic discharge.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a connector for interconnecting aradio-telephone to its base station for signal and power transmission,with a means for preventing electrostatic discharge from damaging thebase station circuitry.

2. Summary of the Prior Art

It is common to find radio-telephones with a plurality of planar contactfaces disposed in a row along a bottom surface of the radio-telephone,for interconnection to power and signal contacts whilst the telephone ispositioned on a cradle on the base station. This electrical connectionprovides not only electrical power for recharging the radio-telephonebatteries, but also signals for controlling and communicating with thetelephone whilst the telephone is on the base station. As the telephoneneeds to be removed and replaced from its cradle, the cradle connector(i.e. the connector positioned in the base station for connection to thecontacts of the radio-telephone) needs to allow for a relatively largevariation in tolerance in the positioning of the radio-telephonecontacts in relation to the size of the connector.

Due to the frequent removal and repositioning of the radio-telephone onits cradle, there is a need for a reliable connection over the life ofthe telephone whilst adjusting to the large tolerances in positioning.There is also a need to protect the circuitry of the base station, inparticular from electrostatic discharges that could occur between anexternal device, or between the contacts of the cradle connector whenexposed to the environment as is the case when the telephone is removed.There is of course a continuous demand on provision of a more compactand cost-effective connection system.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide a cradleconnector that can adjust to a relatively large tolerance in thepositioning of the complementary contacts, in a compact, cost-effectiveand reliable manner.

It is another object of this invention to provide a cradle connectorthat is protected from electrostatic discharge in a cost-effective,compact and reliable manner.

The objects of this invention have been achieved by providing a cradleconnector having a connection end for electrical connection toelectronic circuitry of a base station, and a contact end for connectionto a removable device, wherein supple spring means are provided betweenthe connection end and the contact end, wherein two or more contacts ofthe connector are provided with extensions proximate the contact forabutting against a short circuiting bar positioned within the connector.In an embodiment of this invention, the short circuiting bar isintegrally moulded to a housing of the connector and positionedproximate a top wall of the housing proximate the contacts. The shortcircuiting bar could be in the shape of a wire interconnecting aplurality of cradle connectors during manufacturing for cost-effectivetransportation and handling thereof. The shorting bar could be earthedby connecting one of the contacts to grounding circuitry of the basestation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view through a cradle connector;

FIG. 2 is an isometric view of a plurality of contacts of the cradleconnector, and a shorting bar; and

FIG. 3 is an isometric view of a cradle connector.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, an electrical cradle connector 2 is showncomprising an insulative housing 4 having terminal receiving cavities 6extending from a mating end 8 to a printed circuit board mounting end10, and terminals 12 mounted in the cavities 6. The connector 2 alsocomprises a shorting bar 14 positioned against a top wall 16 of thehousing 4.

The contact 12 comprises a connection section 18, a spring section 20,and a contact section 22. The connection section 18 comprises a printedcircuit board mounting post 24 projecting below the mounting surface 10for insertion into plated through holes of a printed circuit board. Theconnection section 18 could however also be provided with otherconnection means for interconnection to a complementary connector,terminals of a printed circuit board, or other device. The terminal 12is edge-stamped from sheet metal and is therefore substantially planar,and therefore mountable in a compact juxtaposed manner with othercontacts of the connector 2. The terminal receiving cavities 6 have sidewalls 26 between adjacent cavities 6, which also provide a lateral guidefor the contact spring section 20. The contact spring section 20comprises spring beams 28 attached at opposite ends to alternate U-bends30,32 interconnecting the spring beams 28 in a meandering arrangement.

An upper end 34 of the spring section 20 is attached to the contactsection 22 which comprises an arcuate, convex contact surface 36protruding beyond the housing mating surface 8 when the contact section22 is in its uppermost position. The contact surface 36 has asubstantially circular contour over 180°. An extension 38 projects fromthe contact section 22 on an opposing side of the contact section withrespect to the upper end 34 of the spring section 20, the extension 38butting against the shorting bar 14 that extends transversely to theextension 38 of the plurality of terminals 12, when the contacts 22 arein the uppermost position.

The shorting bar 14 can be a conductive member such as a metallic wirethat is overmoulded by the insulative housing 4 such that a portion 40of the shorting bar 14 projects into the cavity 6 for electrical contactwith the extension 38 when in the uppermost position.

Referring to FIG. 2, a plurality of terminals 2,12',12" of the cradleconnector 2 are shown with the housing 4 of the connector removed. Theshorting bar 14 electrically interconnects the plurality of terminals 12with extensions 38, whereby one of the terminals 12' is connected toground circuitry (schematically represented by the symbol 42) of a basestation or device to which the connection section 18 is connected. Thelatter thus grounds all of the terminals 12 interconnected by theshorting bar 14. There may however be a desire not to short circuit someof the terminals 12" to ground, for example power contacts, this beingachieved by eliminating the shorting extensions 38 of these terminals.The latter can be very easily done by simply shearing away the shortingextension 38 of these contacts during the stamping procedure.

A device such as a radio telephone for electrical connection to thecradle connector 2, may comprise substantially planar contact surfacesfor engagement against the arcuate contact surfaces 36 of the terminals12,12',12" whereby the contact surfaces of the device depress thecontacts 22 in opposition to the resiliency of the spring section 20,such that the shorting extensions 38 are disconnected from the shortingbar 14. The radio-telephone may typically have not only a movementtowards the cradle connector but also a rocking movement duringconnection for seating of the radio-telephone into its final blockedposition on the base station to which the cradle connector 2 is securelymounted. The arcuate surfaces 36 over a large angle thus enables a largerotational movement of the complementary device contacts duringinterconnection. The meandering spring section and large number ofspring beams 28 allow a large axial displacement of the contacts 22 suchthat large tolerances in positioning of the complementary devicecontacts with respect thereto, can be tolerated. The contacts 22 areguided effectively in the vertical direction by axial guide walls 44 ofthe housing 4 surrounding the contact section 22. The contact sections22 can thus be depressed by an external object until such object abutsthe mating end 8 of the axial guide walls 44 without overstressing ordamaging the terminals.

The shorting bar 14 can be very cost-effectively produced by providing,for example, simple cylindrical wire whereby the shorting bar could alsobe used to interconnect a plurality of housings 4 which are overmouldedto the wire, the wire serving to hold the housings together duringmanufacturing and handling, the housing separable by shearing away theportion of shorting bar interconnecting adjacent housings during thedesired assembly stage. The shorting bar could also be produced out of astrip of sheet metal, where pilot holes could be provided for improvedease of transportation.

A cap 50 can be positioned over the section of contacts 22 protrudingbeyond the housing 4 for protection thereof when the complementarydevice is removed. The cap is mounted with resilient means (not shown)to the housing 4 and depressible during connection of the complementarydevice (e.g. radio-telephone) in its cradle. The cap 50 is provided withslots 52 to allow passage of the contacts therethrough for connection tothe device.

Advantageously therefore, electrostatic discharge damage of electroniccircuitry interconnected to the cradle connector is avoided by provisionof a simple and cost-effective shorting bar interconnecting terminals ofa cradle connector when the complementary device such as aradio-telephone is removed and the cradle connector terminals exposed.The shorting bar can advantageously also provide a means forinterconnecting a plurality of connector housings or connectors duringmanufacturing and handling for reducing such costs. The cradle connectoris thus compact, cost-effective but nevertheless reliable.

We claim:
 1. A cradle connector for interconnecting a frequentlyremovable and replaceable telephone to a base station, the connectorcomprising an insulative housing having cavities therein, and terminalsmountable within the cavities, the terminals comprising connectionsections for electrical connection to electrical circuitry of the basestation, contact sections for electrical connection to complementarycontacts of the removable device, and supple meandering spring sectionsintermediate the contact and connection sections for allowing resilientbiasing of the contact sections to compensate for relatively largetolerances in positioning of the device, wherein the cradle connectorcomprises a shorting bar electrically interconnecting the terminals whendisconnected to the removable device.
 2. The connector of claim 1wherein the terminals comprise shorting extensions proximate the contactsections for electrical contact with the shorting bar.
 3. The connectorof claim 2 wherein the shorting extension extends from an opposing sideof the contact section to the spring section.
 4. The connector of claim2 wherein one or more terminals of the connector are not electricallyconnectable to the shorting bar, the terminals being of substantiallythe same design as the shorted terminals except for the shortingextensions removed.
 5. The connector of claim 1 wherein the springsection comprises a plurality of spring beams interconnected by U-bendsin a meandering arrangement.
 6. The connector of claim 1 wherein thecontact section is guided in the direction of its resilient axialmovement, by housing guide walls extending axially from a mating end ofthe housing, a mating end of the guide walls providing an abutment toprevent overstressing of the terminal spring sections.
 7. The connectorof claim 1 wherein the shorting bar is inmoulded to the housing.
 8. Theconnector of claim 1 wherein the shorting bar is positioned transverselyto shorting extensions of the terminals.
 9. The connector of claim 8wherein the shorting bar is a wire.
 10. The connector of claim 8 whereinthe shorting bar is a strip of stamped sheet metal with pilot holes fortransportation.
 11. The connector of claim 1 wherein one of theterminals is a ground terminal electrically connected to ground.
 12. Theconnector of claim 10 wherein the shorting bar extends between aplurality of connectors during manufacturing and handling, and portionsthereof are shearable from the housings to separate the connectors. 13.The connector of claim 1 wherein the shorting bar is positioned againsta top housing wall proximate the mating end.
 14. The connector of claim1 wherein the terminal is a substantially planar edge stamped part. 15.The connector of claim 1 wherein the connector comprises a cap coveringthe contacts when the complementary device is removed, the capresiliently biasable towards the mating end during coupling of thecomplementary device for connection of the device to the cradleconnector.
 16. The connector of claim 15 wherein the cap has slots in anupper wall thereof for allowing passage of the contacts therethroughduring depression thereof.